For an application of a focused ion beam (FIB) apparatus, a thin film sample having a thickness of 1 μm or less is widely prepared by using a sputtering function and this thin film sample is observed and evaluated by a transmission electron microscope (TEM). JP-A-04-062748 (Patent Literature 1) discloses that when a sample is tilted by a few degrees to perform thin film processing, a thin film sample having a uniform film thickness is prepared. When this technology is used for preparation finish of a thin film sample, TEM observation can be performed over a wide range with high accuracy.
Further, internal structure analysis in which sample cross section processing using a focused ion beam and scanning electron microscope (SEM) observation are combined is widely performed. JP-A-2008-286652 (Patent Literature 2) proposes a method for using as an image a secondary electron signal from a cross section using a focused ion beam or processing beam and observing a processed surface in real time without interrupting FIB processing and sequentially observing a cross section.
JP-A-2004-127930 (Patent Literature 3) discloses that a aperture position on an objective lens is staggered from an optical axis and a beam out of the optical axis is selectively taken in, and further, when a beam is made incident out of the optical axis of the objective lens to cancel an aberration, a chromatic aberration and a coma aberration are cancelled, respectively, and a beam is irradiated on a sample at a tilt angle of 10° or more. This technology is applicable also to a focused ion beam apparatus.